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TT: Fachverband Tiefe Temperaturen
TT 44: Focus Session: Frontiers of Electronic Structure Theory - Non-Equilibrium Phenomena at the Nano-Scale III (organized by O)
TT 44.8: Vortrag
Dienstag, 1. April 2014, 12:45–13:00, TRE Ma
The exact Hohenberg-Kohn functional for a lattice model — •Tanja Dimitrov1, Heiko Appel1, and Angel Rubio1,2 — 1Fritz-Haber-Institut der MPG, Berlin, Germany — 2NanoBio Spectroscopy group and ETSF, Universidad del País Vasco, San Sebastián, Spain
Standard local exchange-correlation and semi-local functionals in ground-state density functional theory are known for their shortcomings in describing correct charge transfer, dissociation energies of molecular ions, and barriers of chemical reactions [1,2]. To understand the failures of approximate functionals and to gain insight into the behavior of the exact functional, we investigate the exact solution of the many-body Schrödinger equation for a lattice model. Using exact diagonalization, we explicitely construct the exact Hohenberg-Kohn functional and the mapping from densities to wavefunctions. Besides the normal inter-system derivative discontinuity widely discussed in the density-functional theory community, we observe a new feature of the exact functional in the low-density limit. This "intra-system derivative discontinuity" resembles the inter-system derivative discontinuity, but is within the system (work in progress [3]). The description of many physical phenomena linked to charge-transfer processes (both in the static and dynamical regimes) require a proper account of this "intra-system derivative discontinuity".
[1] A. J. Cohen et al. Science 321, 792 (2008).
[2] P. Mori-Sanchez et al., Phys. Rev. Lett. 100, 146401 (2008).
[3] T. Dimitrov, H. Appel, A. Rubio to be published